Plasma Physics Seminar

Dr. Mikhail Sitnov, Johns Hopkins Applied Physics Laboratory Melon seed effect in collisionless magnetic reconnection According to the present paradigm of collisionless magnetic reconnection, the reconnection electric field penetrates into the current sheet near the X-line, where it forms the electron diffusion region, which may further elongate and become unstable with respect to the formation of the secondary magnetic islands. This picture is confirmed for the first time in full-particle simulations with open outflow boundaries, when the reconnection process develops as a result of the current sheet thinning in a 2D self-consistent equilibrium with the X-line separating two magnetotails. Simulations also show, that in equilibria, where the X-line separates two seed regions with the enhanced magnetic flux, the convection electric field, which squeezes the current sheet, penetrates directly to those seeds and accelerates them, forming sharp magnetic pileup structures known as dipolarization fronts. The effect resembles the ejection of a melon seed squeezed between the thumb and fingers. It is consistent with recent results on the linear stability of the tearing mode in magnetotail current sheets. It is also consistent with results of the statistical visualization of the Earth's magnetotail during the onset of substorms based on Geotail data. Return to main page